about IP Addressing

IP Addressing:

Short for Internet Protocol, IP is an address of a computer or other network device on a network using IP or TCP/IP . For example, the number "166.70.10.23" is an example of such an address. These addresses are similar to addresses used on houses and help data reach its appropriate destination on a network. 

There are three classes of available IP ranges: Class A, Class B, and Class C. Each class allows for a range of valid IP addresses. Below is a listing of these addresses.
Class Address Range Supports
Class A 1.0.0.1 to 127.255.255.254 Supports 16 million hosts on each of 127 networks
Class B 128.1.0.1 to 191.255.255.254 Supports 65,000 hosts on each of 16,000 networks.
Class C 192.0.1.1 to 223.255.254.254 Supports 254 hosts on each of 2 million networks.
Ranges 127.x.x.x are reserved for loop back tests, for example, 127.0.0.1. Ranges 255.255.255.255 are used to broadcast to all hosts on the local network.
All IP addresses are broken down into 4 sets of octets that break down into binary to represent the actual IP address. The below chart is a basic example of the basic IP 255.255.255.255.
IP: 255. 255. 255. 255.
Binary value: 11111111. 11111111. 11111111. 11111111.
Octet value: 8 8 8 8


If we were to break down the IP "166.70.10.23", which is the IP address of Computer Hope, you would get the below value.

166. 70. 10. 23
10100110. 01000110. 00001010. 00010111
128+32+4+2=166 64+4+2=70 8+2=10 16+4+2+1=23

There are several IP addresses used or automatically assigned on a network. For example:

166.70.10.0 0 is the automatically assigned network address.
166.70.10.1 1 is the commonly used address used as the gateway.

166.70.10.2 2 is also a commonly used address used for a gateway.
166.70.10.255 255 is automatically assigned on most networks as the broadcast address.



IP Classes
Class A addresses always have the first bit of their IP addresses set to “0”. Since Class A networks have an 8-bit network mask, the use of a leading zero leaves only 7 bits for the network portion of the address, allowing for a maximum of 128 possible network numbers, ranging from 0.0.0.0 – 127.0.0.0. Number 127.x.x.x is reserved for loop back, used for internal testing on the local machine.

Class A addresses contain 7 bits in the network portion giving 27 - 2 = 126 possible networks since all 1's and all 0's are not allowed. Consequently 24 bits remain for the host portion allowing a total of 224 - 2 = 16,777,214 hosts.

Class B addresses always have the first bit set to “1” and their second bit set to “0”. Since Class B addresses have a 16-bit network mask, the use of a leading “10” bit-pattern leaves 14 bits for the network portion of the address.
Class B addresses contain 14 bits in the network portion allowing 214 - 2 = 16,384 possible networks, and 16 bits for the host portion allowing a possible total number of 216 - 2 = 65,534 hosts, ranging from 128.0.0.0 – 181.255.0.0.


Class C addresses have their first two bits set to “1” and their third bit set to “0”. Since Class C addresses have a 24-bit network mask, this leaves 21 bits for the network portion of the address.
Class C addresses contain 21 bits for the network portion giving a possible total of 221 - 2 = 2,097,152 networks, and 8 bits for the host portion giving a possible 28 - 2 = 254 hosts, ranging from 192.0.0.0 – 223.255.255.0.